Inkjet cartridges such as those used in inkjet printers are well known in the art. These inkjet cartridges are generally comprised of a printhead and an integral ink container containing the liquid ink to be supplied to the printhead. During printing, ink is expelled from the printhead through various ejection methods. The ink reservoir is drained during this process and eventually emptied. The structural components of the ink cartridge are durable and will last for numerous charges of ink. A substantial cost involved in the use of inkjet printers is the replacement of cartridges; over the life of the printer this cost is often two or three times the cost of the printer itself. Discarding the entire cartridge after the reservoir is emptied once is an expensive and wasteful practice.
As a result of the high cost and waste involved in disposing of a fully functional, empty cartridge, many users refill ink cartridge reservoirs. Techniques have been developed to replenish the ink reservoirs several times, dramatically extending the life of the cartridge.
There are several known methods and apparati for refilling the reservoirs. These methods require four main steps to refill a cartridge: fill hole access, refilling, fill hole sealing, and priming. Various apparati are employed to assist in performing the four main refilling steps.
Aside from requiring a four-step process, all current methods for refilling ink reservoirs require a certain level of skill to accomplish successfully. As a result, these methods are often messy and may not yield a properly functioning cartridge. Consequently, the widespread acceptance of refilling inkjet cartridges has been limited.
All of the steps of the refill process present the risk of an messy ink spill. Aside from step-specific tools that may be provided by a cartridge refill manufacturer, refill kits may also include a container to hold the cartridge or some absorbent material on which to place the cartridge while the refill process is performed. A common cartridge container is comprised of an open-ended cardboard box lined with absorbent material on the side that will contact the printhead of the cartridge. The purpose of the container or the absorbent material is to minimize the damage caused by ink spills. Containers are used during the entire process, whereas absorbent material may be used as a place-mat for the cartridge during the entire process or merely to wipe the printhead of a cartridge and clean excess ink after the refill process has been performed.
The first step in refilling an inkjet cartridge is to provide access to the ink reservoir through the fill hole. Some cartridges have a small ball that seals the fill hole of the ink reservoir. To access the fill hole, the ball is dislodged into the interior of the reservoir. This operation is accomplished by either an ordinary pressing instrument such as a ball-point pen or a tool that has been specially designed for easier alignment and more ergonomic operation.
Previously refilled cartridges may have a plug covering the fill hole where the small ball originally was located. These cartridges are refilled by removing the plug from the hole. This is often difficult because of the tight fit of the plug and is very difficult to remove by hand.
Other previously refilled cartridges use an Allen head set screw to seal the fill hole. The set screw is removed using an Allen head wrench to unscrew it. This task is time consuming, often taking over thirty seconds to complete. An additional drawback to this method is that the user may accidentally turn the set screw the wrong way, causing the set screw to fall into the reservoir area, preventing its removal for future sealing.
Some cartridges have a septum which is penetrated by a needle to reach the ink reservoir. Once the needle is removed, the septum seals the hole made by the needle and provides an airtight seal. Cartridges may come with a septum from the original manufacturer or a septum may be inserted into the fill hole after dislodging a ball sealing the ink reservoir. However, there are certain disadvantages with this system as well. For instance, the insertion of the septum in a cartridge not originally equipped with one is difficult because of the tight fit between the septum and the small fill hole.
Other cartridges use a stationary vent plug. The plug allows air to pass into the ink reservoir to prevent a vacuum from forming as ink is expelled. At the same time, the plug limits evaporation by minimizing airflow; this is achieved through the use of a small air passageway which can make several right angle turns. This results in a passageway too small and too angled for ink to be delivered through effectively. In this type of cartridge, two solutions to accessing the reservoir exist. The first is simply to remove the vent plug entirely. The removal of the vent plug is difficult and requires special tools to grip and pull the vent plug out of its resting place. A second method, more commonly used in refill processes, is to create a hole in the vent plug large enough for ink to pass through quickly. The hole may be made by a variety of hand driven tools such as an auger or screw-eye rotated to bore a hole through the vent plug, as disclosed in U.S. Copyright Reg. No. TX 2-548-168 and later stated in U.S. Pat. No. 5,199,470. Other methods, as disclosed by U.S. Pat. No. 4,589,000, include piercing a hole through the vent plug with a sharp pointed object by hand, but this requires considerable force to perform.
Some cartridges have a top covering both the cartridge and fill holes which is not in direct contact with the otherwise unobstructed fill holes. This reduces evaporation and also makes the cartridge easier to install in the printer. In order to refill this cartridge, the top must be removed by breaking the ultrasonic bonds that hold it in place. This is difficult to do and usually requires special tools to ensure that force is applied to the correct areas of the cartridge. Once the top is broken off, the fill holes are exposed and ready to be filled. Other methods replace the old top with one with columns giving constant access to the fill holes. Some refill methods provide a cartridge that has been modified by the refiller to give access to the fill holes.
The last category of cartridges has a constantly exposed fill hole. These cartridges rely on a foam sponge and/or sit upright to keep the contents of the ink reservoir from leaking and/or evaporating excessively.
The second step in the cartridge refilling process is the actual filling of the ink reservoir through the fill hole. A common method, such as disclosed in U.S. Pat. No. 5,199,470, employs the use of an accordion-style bellows bottle commonly known as a Boston bottle. The user compresses the bottle to force ink out of the container through the fill hole and into the reservoir. This method could result in ink spilling out of the cartridge and injector tube, creating a mess. Another drawback of this method is that not all ink can be easily drained out of the bellows bottle unless it is held at a specific orientation and is allowed to breathe air. Also, the bellows bottle is hard to compress.
Another popular method of filling the ink reservoir employs a non-reusable syringe as disclosed in U.S. Pat. No. 5,232,447 or a standard syringe to inject ink into the reservoir. The injector tube (needle) of the syringe is inserted by hand into the reservoir through the fill hole. Then the plunger of the refill is pressed by hand until the proper amount of ink has been dispensed or the refill unit is empty. This method also can prove to be messy, but it is easier to use and does not waste as much ink as the bellows bottle method.
The use of squeeze bottles to fill ink reservoirs is also popular. These bottles are not Boston bottles, but do dispense ink by compression. The injector is inserted through the fill hole into the reservoir. At that point the sides of the bottle are squeezed causing the ink to be dispensed. Again, this process can be messy and difficult and requires special orientation and air breathing to dispense all ink.
The last of the methods known in the art of refilling cartridges takes advantage of gravity to dispense ink into the reservoir. The ink container may be of any shape or size containing one recharge of ink. An injector tube attached to the container passes through the fill hole into the reservoir carrying the ink. The ink flow begins when a small air hole is punctured in the top of the ink container releasing the vacuum that impedes the flow of ink from the container. A major drawback to this method is that it takes a long time, often several minutes, to refill a cartridge. The ink dispensing process is not easily stopped once started and is impossible to stop in cartridges that do not use a septum. This can result in ink spills when the cartridge is overfilled or the apparatus is accidentally knocked over.
Once the ink reservoir has been refilled, the third step of the cartridge recycling process is to seal the fill hole. The simplest fill hole resealing method requires a rubber plug to be pressed into the fill hole by hand. Plugs make an excellent seal, but requires the exertion of uncomfortable amounts of force. Residual ink around the fill hole may stain the user's hands while performing this step from or, worse yet, accidentally tilting or tipping over the cartridge during this process could cause an ink spill.
An alternative to inserting a plug in small areas where it is hard for the user to manipulate his/her hands is to use an Allen head set screw. The set screw is twisted into place by a hex key after filling. The drawbacks to this method of sealing are the long amount of time to twist the screw into place, the high level of dexterity required to twist the screw into place, and the chance that the user may twist the set screw too tightly causing it to fall into the reservoir where it can not be reached.
The vent plug is simply replaced on cartridges with removable vent plugs. The plug is either pushed back into place by hand or using an auger. This is a simple process, but may result in ink on the user's hands from residual ink around the file hole.
Some refill kits supply a new apparatus to cover the area where the vent holes are located to replace one removed at the beginning of the refill process. Other similar ideas use an additional piece to join the cover to the file hole area. These pieces are press fit into place by the user and are generally simple to use.
Cartridges with a septum covering the reservoir area are automatically sealed as the filling device is withdrawn. The septum forms an air and liquid tight seal and no work is required on the part of the user to seal the reservoir.
The last option after filling the reservoir is to leave the fill hole open. On certain cartridges, where evaporation and ink leakage are not concerns, the fill hole may be left open. In fact some cartridges come from the original manufacturer with an open fill hole. This method, like the septum, requires no work on the part of the user.
The fourth step of the inkjet cartridge recycling process requires the cartridge to be primed, usually by the injection of air into the sealed cartridge. A primed cartridge has the pressure of the ink at the nozzle within a specific range, allowing the cartridge to function. Forcing air through the vent will prime the cartridge. Ink is expelled through the printhead as air is forced into the reservoir through the vent hole by squeezing a bulb, depressing a syringe, or by blowing into the vent hole. Any air that may have been introduced into the printhead before or during refilling is expelled along with the ink in this process. The resulting cartridge is primed and ready to print just like an original factory cartridge. The disadvantage of the current methods of priming available is that the process requires the user to perform an extra step by using an additional apparatus or by blowing into the cartridge with his/her mouth.
Some inkjet cartridges have internal pressure control mechanisms that are used to maintain the slight negative pressure required for inkjet printing. The pressure control mechanisms are comprised of air bags residing in the reservoir. In order to prevent internal pressure from equalizing with external pressure when an ink cartridge reservoir is refilled, some refill methods prevent the pressure control mechanisms from adjusting during the refill process. This is done by covering the vent hole (leading to the air bags) before opening the fill hole, during refilling, and until after the fill hole has been sealed. Manufacturers of cartridge refill kits may supply a specialized tool for this task. The result is that the pressure control mechanisms are maintained in an excessively expanded position and occupy significantly more volume of the reservoir than is necessary for proper functioning after refilling. This prevents a full replenishment of the reservoir as the available volume of the reservoir will only hold approximately three-fourths of the original amount of ink.
Other methods allow the pressure control mechanisms to adjust during the refill process and then require the mechanisms to be adjusted to the appropriate levels after filling the reservoir. This allows a full replenishment of the ink reservoir but requires more work on the part of the user. These methods generally rely on a squeezable "priming" bulb to inflate the air bags after filling the reservoir. This can be done either before or after sealing the fill hole. When the fill hole is sealed after the air bags are inflated, a certain volume of air is injected into the air bags, thus displacing a certain amount of volume in the reservoir. The fill hole is then sealed while the air bags are still in the inflated position and volume of the reservoir (and the air in it) is at a decreased level. Once the fill hole is sealed, the inflation device is removed from the vent hole and the air bags partially deflate, thus forming a negative pressure in the reservoir as the volume increases, but the amount of air and ink in the reservoir is unchanged.
Two methods can be used to adjust the pressure control mechanisms after the fill hole has been sealed. The first method uses a squeezable "priming" bulb or syringe to inflate the air bags after sealing the fill hole. The pressure in the reservoir is at ambient pressure when the fill hole is sealed. When the vent hole is inflated, the air bags expand and force ink out of the reservoir through the printhead and bubble generator. This is caused by increased pressure in the reservoir from the air bags attempting to expand and reduce the reservoir volume. The user is instructed to continue to expel ink several times until the cartridge stops leaking. Once enough ink has been expelled from the cartridge the required negative pressure is achieved since no additional air is allowed into the reservoir. This is a messy method and usually two or three milliliters of ink are expelled from the cartridge before it is primed.
The second method of adjusting the pressure control mechanisms after the fill hole has been sealed is similar to the first except that the air bags are not inflated to expel ink. Instead this method relies on gravitational force and the fact that the reservoir is not at the correct negative pressure to achieve a slow drip of ink from the printhead. This continues until the same amount of ink is expelled and the correct negative pressure is achieved as in the previous method; the user is not required to do anything except wait ten to fifteen minutes.
One type of cartridge, comprising an ink bag and a septum, does not require any work on the part of the user to be primed. No air is in the cartridge as it is sealed off by the septum and no air is injected during the refilling process. These cartridges are the simplest type to prime as the printer automatically primes the ink tubes and does not even require the user to request priming.
As mentioned, the known art includes several devices to assist in the refill process. Most refill devices can be classified as specialized tools that assist one particular step of the refill process. There is at least one known device that attempts to combine the steps into a process that is easier for the user. The known device comprises a washable, durable container to hold a cartridge during the refill process. The container has rubber plugs at the bottom to seal the print orifices and bubble generator, thereby preventing the flow of ink. A two-piece cap is manually inserted on the container one piece at a time. The first piece seals the vent hole. The second piece opens the fill hole of a cartridge by punching out the ball seal. An ink vessel is then coupled to the cap to fill the cartridge ink reservoir via gravitational flow. After the ink has drained from the vessel, the second piece of the cap is removed and the fill hole is manually sealed with a rubber plug. The system is slow because of its use of gravitational flow for the fill process. It also has no priming means. Consequently, the ink reservoir cannot be completely filled if the cartridge uses an air bag pressurization system. The problem of ink spillage is not eliminated by the system: large amounts of ink may be spilled if the device is toppled during the refill process.
Accordingly, it is seen that there is a need in the art for an efficient, easy-to-use, inexpensive cartridge refilling device that may be used by an individual to refill an inkjet cartridge. The device of the present invention provides a solution to this need.